Adsorption isotherms resins

The 2eohte and the resin adsorbents show different adsorption isotherm characteristics, particularly at higher concentration (51). The resin adsorbent isotherm is slightly concave upward, whereas the 2eohte isotherm is linear, or even slightly concave downward. Resins, therefore, have an advantage in a UOP Sarex operation that involves high feed-soHds concentration. 

Figure 12.9 illustrates the influence of temperature on iodate removal. In the case of desorption at 25°C, iodate will remain on the resin particles. Flowever, desorption is fully completed at 50°C. Figure 12.10 provides an example of an adsorption isotherm of the iodate ion. 

We stress the fact that these relations are valid only for linear adsorption isotherms [sugars on cationic resins, diluted feed on silica (usually less than 10 g/liter)]. 

Figure 3. Comparison of nitrogen, benzene and water vapor adsorption isotherms on PHD and MEA resins.

The synthesis of phenolic-formaldehyde and melamine-formaldehyde resins in the presence of fumed silica allows obtaining porous organic materials with a differentiated porous structure and surface properties. The pore characteristics of the studied resins in dry state were determined from nitrogen adsorption isotherms. The differences in surface character of the synthesized polymers were estimated satisfactorily by XPS spectra showing the presence of various functional groups. The adsorption/desorption mechanism of water and benzene on the investigated porous polymers was different due to differentiated hydrophobicity of the bulk material. 

Adsorption. Organic compounds are adsorbed on activated carbon and synthetic resins (eg, XAD-2 and XAD-4, Rohm and Haas Co.). This technique depends on the properties of the compound being removed and the regenerative capabiHty of the adsorbent. The EPA has developed carbon-adsorption isotherms for various toxic organic compounds, and the results are shown in Table 7 (36). The following compounds are not adsorbed on activated carbon acetone cyanohydrin, butylamine, choline chloride, cyclohexylamine, diethylene glycol, ethylenediamine, hexamethylenediamine, morpholine, and triethanolamine. 

The SMB separation uses an ion-exchanger resin whose non linear adsorption isotherm is described by Eq. 8.48 ... 

Figure 3. Adsorption isotherms of free XAD-4 resins and immobilized XAD-4 resins in K-carrageenan in aqueous CH solution and CH fermentation broth. Key O, aqueous, free resin A, aqueous, immobilized resin , broth, free resin A, broth, immobilized resin.

In order to demonstrate that the adsorbents perform the same way as in the case of synthetic gold bromide solution, the actual leach products were produced and used to create adsorption isotherms for both resin types and activated carbon. Furthermore, the filtrates of isotherm products... 

In order to use expanded-bed adsorption for nonpolar, water-insoluble products in a fermentation broth, it is necessaiy to add a water-miscible solvent initially to solubilize the product. Some common solvents used to solubilize nonpolar products are shown in Table 8. When solvents are used to solubilize a nonpolar product, it is essential to use the minimum volume of solvent required, as addition of excess solvent decreases the capacity of the adsorbent. This decrease in adsorptive capacity occurs for two reasons. The resin adsorption isotherm for the product is decreased owing to the excess solvent. Also, excess solvent decreases the product concentration in the liquid phase, and when operating in the linear range of the adsorption isotherm, this lower product concentration leads to a proportional decrease in the resin capacity. Operation in the linear range is the usual situation for the dilute-product solution encountered in fermentation broth in the early stages of research and development. However, the solvent addition does have an important beneficial side effect that increases procedure productivity. Solvent added to whole broth decreases both the specific gravity and the... 

For example, Yoon et al. report that the water adsorption isotherm for an immobilized lipase (Lipozyme IM) and pure scCOa follows eq (4.9-1) where w is the water concentration in the enzyme support (wt%), C is the water concentration in CO2 (mM) and Co is the water solubility in CO2 (mM) under system pressure and temperature [41], Marty et al. report water adsorption isotherms (33 °C, 40 °C, 50 °C) between a microporous anionic resin support and ethanol containing SCCO2 at three pressures (110, 130 and 170 bar) [9]. Water partitioning data for an anionic resin support and pure SCCO2 are also available [42,43]. 

Figure 1. Adsorption isotherms of CALB onto resins that differ in particle size. (Reproducedfrom hmgmar 2007, 23, 1381-1387. Copyright 2007 American...

A series of close-to-spherical styrene/DVB resins of varying particle size and pore diameter were employed as supports for non-covalent adsorptive attachment of CALB by hydrophobic interaction. The effect of matrix particle and pore size on CALB i) adsorption isotherms, ii) fraction of active sites, iii) distribution within supports, and iv) catalytic activity for s-CL ring-opening polymerizations and adipic acid/l,8-octanediol polycondensations is reported. Important differences in the above for CALB immobilized on methyl methacrylate and styrene/DVB resins were found. The lessons learned herein provide a basis to others that seek to design optimal immobilized enzyme catalysts for low molar mass and polymerization reactions. 

BET) analysis for their adsorption isotherm. Hommel and Legrand [131 followed this approach for the study of the retention of 7-undecyi-8-hydrox-yquinoline on Amberlite XAD7. The amount of extractant (0.27 0.07 g/g) needed to form a monolayer on the surface of the resin was determined. Their results strengthen the assumption that the retention process is a result of competitive processes between resin, water, and the extractant. 

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